Apparatus for producing cellulose from fibrous materials.



G. H. MARSHALL. I

APPARATUS FOR PRODUCING GELLULOSE FBQM PIBROUS MATERIALS.

APPLICATION FILED Jun. 10, 1909.

968,864. Patented Aug. 30, 1910.

19i hwom GEORGE H. MARSHALL, OF ROANOKE RAPIDS, NORTH CAROLINA.

APPARATUS FOR PRODUCING CELLULOSE FROM FIBROUS MATERIALS.

Specification of Letters Patent.

Patented Aug. 30, 1910.

Application filed June 10, 1909. Serial No. 501,379.

To all whom it may concern:

Be it known that I, GEORGE E. MARSHALL, a citizen of the United States,residing at Roanoke Rapids, in the county of Halifax and State of NorthCarolina, have invented certain new and useful Improvements in Apparatusfor Producing Cellulose from Fibrous Materials, of which the followingis a specification, reference being had to the accompanying drawings.

This invention relates to the production of pure cellulose fibers forpaper making or textile purposes, from such materials as flax straw,cornstalks, sorghum, bagasse, sugar cane, reed grasses, or analogoussubstances, and has for its object to provide an improved apparatus forthe treatment of such raw material in a suitable manner to accomplishthis desired result.

The process carried out by my improved apparatus, for which I have filedan application for United States Letters Patent of even date herewith,is essentially continuous although it has two stages, the result of thefirst stage being the softening of the piths and woody incrustingmatter, and removing the sugars and gums and some of the ce menting orincrusting materials which surround the cellulose fibers propen. In bothstages of the process I make use of my improved mechanism comprisingclosed vessels, preferably elongated rotating types of boilers, ordigesters, a series of two or more of these vessels being employedwhereby a greater economy is secured. In the first stage of the processthe materials are treated to a partial reduction or softening operation, whereby they are rendered more receptive for the second stage, thepithy or woody matters being partially exploded and their cellular orglobular formation thereby broken up, and a portion of the incrustingmatters removed by blowing under pressure. In this stage I employ a highsteam pressure in one of the digesters, in connection with water andneutralizing substances of a weak alkaline nature, such as chalk,limestone dust, or lime, the object of the neutralizing substances beingto prevent the accumulation of acids due to the disintegration of thesugars and incrusting matters by the heat due to the high steampressure. I

employ from ten to twenty per cent. of the neutralizing substances,according to the condltion of the raw materlal belng treated. If thematerial 1s green, a lesser amount generally suflices, but if thematerial is dry and hard, a greater amount is required. In the secondstage of the process I employ in the digesters, strong alkaline liquorsin the nature of solutions of sodium carbonate, sodium hydrate, orsodium sulfid, or a mixture of these, according to whether the materialis old, dry, green or new.

In order that persons skilled in the art may be enabled to construct andoperate my improved apparatus, I will now proceed to fully describe thesame in connection with the accompanying drawing which is a diagrammaticillustration, some parts being broken away, and parts being shown insection, the driving power being understood to be any suitable motor orengine.

Referring specifically to the drawing, 1 and 2 indicate two elongatedrotary boilers or digesters, which are provided with trunnions 3, 4, 5and 6, journaled in suitable bearings 7, the trunnions 3 and 5 beinghollow to permit of the passage of steam therethrough to the digester,suitable steam pipes 8, 9, leading from any source of steam (not shown)being connected with said hollow trunnions and being provided with outoff valves 10 and 11. The trunnions 4 and 6 are solid and, beingcontinued beyond their bearings, are provided with gears 12, 13, meshingwith pinions 14, 15 on counter shafts 16, 17, said shafts being drivenby belting from any suitable driving pulley (not shown) engaged on fastand loose pulleys 18, 19, whereby the digesters may be rotated on thehorizontal axes of the trunnions, and stopped, when desired, by shiftingthe belts from the fast to the loose pulleys in the ordinary manner. Thedigesters are each provided with an opening or manhole at one end,closable by means of covers 20, 21, which may be secured in a steamtight manner by means of the gaskets 22, 23 and bolts 24, 25. Thematerials to be treated are placed in the digesters through themanholes, screens 26, 27, near the opposite ends of said digesters,preventing the passage or discharge of the treated material throughspouts 28, 29 at the opposite ends which are provided for dischargingthe liquid contents of the digesters and are provided with suitableblow-ofi valves 30, 31.

At 32 is indicated a blow-ofl or exhaust pipe, which may be connectedwith either s out 23 or 29, by a swing pipe 33, said b ow-oif pipepassing (in the form of a coil 34) through a water-heater 35, to theatmosphere, the water-heater being provided with a water-inlet pipe 36with valve 37, whereby cold water may be admitted, and a discharge pipe38 whereby hot water may be forced from the heater by a pump 39 througha line of piping as hereinafter explained.

At 40 is shown a tank, or agitator, from which leads a pipe 41 having avalve 42, which pipe, beyond said valve, is connected with the pump 39by a pipe 43 having a valve 44. The pipe 41 extends to and joins across-over pipe 45 leading from steam pipe 8 to steam pipe 9, and abranch pipe 46 also leads from said pipe 41 to the cross-over pipe, thepipes 41, 45 and 46 being supplied with suitable valves 47 48, 49 and50. A vent pipe 51 leads from the cross-over pipe 45 to the atmosphereand is provided with a valve 52.

Steam entering the digesters through pipes Sand 9 is properlydistributed and delivered therein by suitable intake pipes 53 and 54leading into the body of the material contents.

The first stage of my process is carried out as follows: The materialsto be treated are first introduced into the digesters 1 and 2 either ina whole or broken condition as may be preferred for convenience inhandling. After the full amount of material is in the digester 1, thenecessary amount of water which has been previously mixed in theagitator 40 with the chalk, limestone, lime, or other neutralizingsubstance, is run into said digester through pipe 41. The cover 20 isthen placed on the digester and securely bolted down on the gasket 22 tomake a steam tight joint. All of the valves except steam valve 10 beingclosed, the steam is turned on slowly and allowed to enter the digester1, (which is now rotated), for several minutes, or until a pressure ofsay thirty pounds is reached, when the steam valve 10 is closed, thedigester being stopped in a vertical position, with the manhole enduppermost. All valves being now closed the valves 48 and 52 are opened,thus allowing the air contained in the digester in a heated condition topass through these valves and thence to the atmosphere. After all theair in the digester is exhausted, the valves 48 and 52 are closed andthe steam valve 10 again opened, and the digester again rotated. Thesteam pressure is now allowed to rise slowly to eighty pounds, say inhalf an hour. During the next half hour the steam pressure is allowed torise to one hundred pounds, and during the next succeeding half hour,the pressure is allowed to rise to one hundred and fifty pounds. Thefinal pressure of one hundred and fifty pounds having been reached inone and one-half hours, the digester is then stopped, in a verticalposition, with the blow-off valve 30 at the lower extremity, andconnection is then made with the swing pipe 33. The blow-0E valve 30 isnow partially opened, allowing the liquor from the digester to passthrough the screen, or strainer bottom 26, out through valve 30, pipe33, pipe 32 and coil 34 in the heating tank 35, to the atmosphere. Theblowing off is continued for five minutes, with the live steam valve 10open, after which time the live steam valve is tightly closed and theblow-off valve 30 is opened wide, as quickly as possible, thus allowingthe pressure in the digester to reduce in the shortest possible time,and there by creating an expansive or exploding effect upon the piths orwoody portions of the stalks, as in the flax straw. The pressure due tosteam having at this point subsided, the water in tank 35, which hasbeen heated by the blow-off steam passing through coil 34, is now pumpedby pump 39 through pipe 43, valve 44, pipe 41, valve 48 and pipe 8, intothe digester and forced through the material inside of it and outthrough swing pipe 33 and blow-off pipe 32 to the sewer, thus washingout any residual matter which was not expelled during the blowing-oifoperation. The first stage of the process is now completed and duringthis operation, a charge of-liquor has been supplied to tank 40containing sodium carbonate, sodium hydrate, sodium sulfid, or a mixtureof these three according to the material to be treated, the strengthranging from three to six per cent, being weaker for green, and strongerfor dry or seasoned materials. This liquor above mentioned is nowintroduced into the digester and its contents and the digester beingagain set in rotation and the live steam valve 10 partially opened, thepressure being allowed to rise again to say thirty pounds, and then theair and entrained gases are blown to the atmosphere as in the firststage after which the steam pressure is raised as follows: viz., duringthe first half hour to eighty pounds, during the second half hour to onehundred and twenty pounds, and during the third half hour to one hundredand sixty pounds. During these operations in digester 1, a similarcharge of the raw material has been placed in digester 2, and is readyfor the first steam, so that as the steam in digester 1 has reached apressure of one hundred and sixty' pounds, the steam is shut ofi' fromthat digester and is blown from it through cross-over pipe 45 and pipe 9into digester 2, the contents of digester 2 being thereby heated tothirty pounds pressure by this blow-oil steam from digester 1, therebyefiecting a considerable economy in steam. When through the blowingoperation just above mentioned, the pressure has arisen in digester 2 tothirty pounds, all

valves are closed and digester 1 which is standing in a verticalposition, is connected up to the blOW-Ofl pipe 32 and the remainingpressure blown to any desired point, carrying with it the resultantliquors which may be treated for the recovery of the soda, if desired.After the resultant liquors have been blown out, hotwater, heated by thesecond blow-01f, is introduced into the digester 1, and forced throughthe contents of the same out through the blow-off pipe 32 to any desiredpoint. The contents of digester 1 may then be dumped by rotating thedigester to bring the manhole to the bottom and the treated materialconveyed to any desired point for washing and bleaching by any of thepresent well known methods.

Having thus fully described my invention, what I claim as new, anddesire to secure by Letters Patent, is

An apparatus of the character described comprising a pair of rotarydigesters having horizontal trunnions rotatable in bear ings, onetrunnion of each digester being hollow, a covered inlet at one end ofeach of the digesters for the material to be treated, a screen covered,valve controlled outlet at the other end of each of the digesters,independent means for rotating the digesters, a pipe extending throughthe hollow trunnion of each of the digesters and having its inner endupturned, a valve controlled steam pipe in communication with each ofthe first mentioned pipes, a valve controlled crossover pipeincommunication with the first mentioned pipe, a valve controlled ventpipe in communication with said cross-over pipe, an agitator tank, avalve controlled outlet for said tank and provided with valve controlledbranches communicating with the first mentioned pipes, 21 blow-off pipe,a Water heater containing a heatin coil in communication with saidblow-0d pipe, a swing pipe connected with said blow-ofi' pipe andadapted to be connected to the outlet of either of the two digesters, apump having its inlet in communication with said water heater, and avalve controlled outlet for said pump in communication with the outletpipe of said tank.

In testimony whereof I hereunto aflix my signature in the presence oftwo witnesses.

GEO. H. MARSHALL.

Witnesses THOS. R. H. MURPHY, J. T. CHASE.

